Wafer containers and reticle pods generally are sealed containers known as FOUPs (front opening unified pods), FOSBs (front opening shipping boxes), or SMIF (standard mechanical interface) pods. These containers provide a microenvironment to isolate and control the environment surrounding a wafers and substrates used in manufacturing integrated circuits, during storage, transport and processing of the materials. Processing of such materials traditionally has been carried out in a particulate free environment generally known as a “clean room”. However, maintenance of such “clean rooms” in a contaminant free state can require a great deal of care and effort, particularly during processing of the materials.
The internal atmosphere of such microenvironments can be more readily controlled and maintained. Often, such containers are purgible with inert gas or clean dry air (CDA) or extra CDA. It has been observed that contamination of reticles in such containers can be caused not only by discrete particles but also by hazing occurring on wafers or reticles. See Publication WO 2007/149513 A2, owned by the owner of the instant application, which is incorporated herein by reference and included in the Appendix to this application. Such hazing can also occur on wafers in wafer containers and be detrimental thereto, see U.S. Pat. No. 5,346,518 which is incorporated herein by reference. Also relevant, U.S. Pat. No. 6,042,651, owned by the owner of the instant application, discloses using nozzled towers in bottom opening SMIF pods and a front opening wafer container that uses wafer shelf assemblies as purge outlets. Problems associated with such structures and optimal use of such structures has not been adequately addressed.
For example, the use of desiccants and vapor getters in substrate containers typically require removal or disassembly of same before washing and such substrate containers as the fluids utilized can destroy the media for filtering and/or vapor absorption. Moreover, purge port plumbing within substrate containers is, aside from the media issues, difficult to clean and dry due to the enclosed areas used for transferring purge gases. A means for facilitating cleaning of such substrate containers without disassembly and removal of media and purge components would be very advantageous. Particularly, problematic in cleaning are free standing towers such as disclosed in U.S. Pat. No. 6,042,651. Moreover, such towers are subject to movement and potential dislocation due to their conventional positioning where they may be inadvertently contacted and their connection only at the base of the substrate container. Better positioning and attachment methods and structures would be advantageous, particularly methods that do not rely on holes or fasteners that extend through walls or other barriers separating the enclosed interior of the container from the exterior.
The use of discrete towers in a front opening pod, the use of more than one discharge tower, and the optimal placement and securement of discharge towers or tubular environmental control components has not heretofore been adequately considered and optimized to satisfactorily address reliability, haze, contamination and particulate control, and cleaning issues in front opening large diameter wafer containers. As a transition is made from 300 mm wafers to 450 mm wafers, improvements in these areas will be even more important.